Comments (7)

The milk part of those may have a hard time, however, you could blanch them and then freeze. Dunk them in boiling water for exactly 3 minutes, the straight into a bowl of ice water, then bag and freeze. I am not sure on the mushrooms - but you may be able to freeze them similar to the celery.

I think if you have a bechamel base (equal parts butter/oil and flour combined, then milk/cream whisked in and reduced to thicken), it should work. The celery and mushrooms could be thrown in to steep in the liquid, then strained out if you prefer, or maybe even pureed in a blender or with a stick immersion blender.

There are certainly a lot of frozen macaroni and cheese dinners and other meals with that kind of sauce on the market, your soup would just be a thinner, soup-like consistency.

Are you wanting to make that recipe that floats around here a lot for "homemade cream of chicken" and then put in celery and or mushrooms instead (or in addition)? If that is the case, and you want to have it on hand for recipes that call for cream-of soups, then I think it will probably work - but as pp suggested, I would thaw it carefully (in the fridge over time, not in the microwave) and then you will probably need to stir/whisk it a bit to get it smooth.